docs: def add_sideplot(self, along, pad=0, height=0.75, ymin=0, ymax=1.1):
          """Add a side axis.
  
          Parameters
          ----------
          along : {'x', 'y'}
              Axis to add along.
          pad : float (optional)
              Side axis pad. Default is 0.
          height : float (optional)
              Side axis height. Default is 0.
          """
          # divider should only be created once
          if hasattr(self, "divider"):
              divider = self.divider
          else:
              divider = make_axes_locatable(self)
              setattr(self, "divider", divider)
          # create
          if along == "x":
              ax = self.sidex = divider.append_axes("top", height, pad=pad, sharex=self)
          elif along == "y":
              ax = self.sidey = divider.append_axes("right", height, pad=pad, sharey=self)
              ax.transposed = True
          # beautify
          if along == "x":
              ax.set_ylim(ymin, ymax)
          elif along == "y":
              ax.set_xlim(ymin, ymax)
          ax.autoscale(enable=False)
          ax.set_adjustable("box")
          ax.is_sideplot = True
          plt.setp(ax.get_xticklabels(), visible=False)
          plt.setp(ax.get_yticklabels(), visible=False)
          ax.tick_params(axis="both", which="both", length=0)
          return ax